Injectable physiologically adaptive intraocular lenses (iol&#39;s)

ABSTRACT

A device and method for forming an adaptive optic in the capsule of a human eye is disclosed, comprising a capsular interface enclosing an optically acceptable medium. The device establishes a physiologic range of optical power in response to a range of ciliary contractile states. The preferred bi-phasic medium of the device is comprised of a solid three dimensional polymeric network suspended in a liquid aqueous phase and bonded to a capsular interface. The polymeric network provides shape to the capsular interface, optical power, and a physiologic response to the suspensory ligament. The three dimensional network of the bi-phasic medium mimics the stacked fiber configuration and elasticity of a natural lens. An alternative embodiment utilizing a single phase medium is also disclosed with associated structural features provided in the capsular interface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/096,729 filed Apr. 28, 2011, which claims the benefit of priority toU.S. Provisional Application Ser. No. 61/329,447, filed Apr. 29, 2010.The entire contents of each of the foregoing applications areincorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to treating eyes, and more particularly todevices and methods for forming an adaptive optic in the capsule of ahuman eye.

2. Description of Related Art

Referring to FIGS. 1A and 1B, the zonule of Zinn (Zinn's membrane,ciliary zonule) is a ring of fibrous strands 52 connecting the ciliarybody with the crystalline lens 54 of the eye. The zonule of Zinn issplit into two layers: a thin layer which lines the hyaloid fossa and athicker layer which is a collection of zonular fibers. Collectively, thefibers are known as the suspensory ligament of the lens. The action ofthe suspensory ligament is to place tension on the capsule 56 (shown inpartial section view) of the lens 54 to keep it centered on the eye.While the suspensory ligament accommodates the optics of the eye bychanging the magnitude of tension on the capsule, the capsule isnevertheless in tension through all accommodative states of a normaleye. Correspondingly, when an intraocular lens (IOL) is placed in theeye it is not bonded to the capsule and hence is not in tension.Currently the only means for centering an IOL implanted within thecapsule is to provide structure which creates forces between the IOL andthe capsule to center the IOL. This is accomplished with haptics, smallloop shaped springs on the equator of the lens, which apply acompressive force along the equator of the lens. The net effect is toincrease the tension placed on the capsule at the equator, renderingineffective any changes in the ciliary muscle fibers which otherwisewould change the shape of a material lens to provide accommodation andalter the power of the lens. In the normal lens, as the ciliary musclescontract (like a sphincter) the zonules relax and the lens becomesrounder to provide accommodation and variable power. Today's flat IOLsneed haptics to keep the IOL in place. The haptics do not maintain thenatural shape of the capsular bag. The zonular fibers surrounding thecapsule are thus relaxed beyond the normal range of contraction of theciliary muscle. Thus the ciliary muscle cannot relax the zonular fibersmore, and the capsular bag remains in a position of over accommodation.Thus, physiological accommodation is not possible with any type of thinand flat IOL. It is a further object of the present invention to providean IOL with an approximately ellipsoidal profile.

This release of tension of the zonular fibers causes the lens to becomemore spherical, thereby increasing the power of the lens to focus onnear objects.

Referring again to FIGS. 1A and 1B, to understand the sensitivity of theaccommodative function, it is important to recognize there are bothradial 62 and anterior-posterior (AP) zonular fibers (64 and 66).According to the Schachar hypothesis when the ciliary muscle contracts,AP zonular tension is increased (the angle between 64 and 66 increases)while radial zonular fiber tension decreases. The increase in AP zonulartension occurs peri-circumferentially causing the central surfaces ofthe crystalline lens 54 to steepen, the central thickness of the lens toincrease (increasing the anterior-posterior diameter), and theperipheral surfaces of the lens to flatten. While the tension on APzonules is increased during accommodation, the radial zonules aresimultaneously relaxing.

As a consequence of the changes in lens shape during human in vivoaccommodation, the central optical power of the lens increases andspherical aberration of the lens shifts in the negative direction.Because of the increased AP zonular tension on the lens duringaccommodation, the surface tension of the lens capsule is increaseddespite the reduction in radial tension and the lens remains stable andunaffected by gravity. To be more specific, the surface tension isactually the interaction between the AP zonular tension and theanterior-posterior connectivity provided by the fibular structure 70 ofthe lens 54. This is an important feature striking a compromise betweenlow modulus and resistance to distortion by gravity. The same shapechanges that occur to the crystalline lens during accommodation areobserved when circumferential tension is applied to any encapsulatedbiconvex object that encloses a minimally compressible material (volumechange less than approximately 3%) and has an elliptical profile at theequator of the lens with an aspect ratio≤0.6 (minor axis/major axisratio). The fibular structure of the lens is likely responsible formaintaining the aspect ratio below 0.6 of the elliptical profile.Circumferential tension is very efficient when applied to biconvexobjects that have a profile with an aspect ratio≤0.6. Minimalcircumferential tension tends to flatten the equator of the lens,slightly increasing the lateral equatorial diameter and causing a largeincrease in central curvature resulting in a more spherical-shaped lens.Vertebrates that have lenses with aspect ratios≤0.6 have high amplitudesof accommodation; e.g., primates and falcons, while those vertebrateswith lenticular aspect ratios>0.6 have low amplitudes of accommodation;e.g. owls and antelopes.

The decline in the amplitude of accommodation eventually results in theclinical manifestation of presbyopia. It has been widely suggested thatthe age-related decline in accommodation that leads to presbyopia occursas a consequence of sclerosis (hardening) of the lens. However, the lensdoes not become sclerotic until after 40 years of age. In fact, thegreatest decline in the amplitude of accommodation occurs duringchildhood, prior to the time that any change in hardness of the lens hasbeen found. The decline in accommodative amplitude, rapid in childhoodand slow thereafter, follows a logarithmic pattern that is similar tothat of the increase in the equatorial diameter of the lens, which isthe most likely basis for the accommodative loss. As the equatorialdiameter of the lens continuously increases over life, baseline ciliarytension simultaneously declines. This results in a reduction in baselineciliary muscle length that is associated with both lens growth andincreasing age. Since the ciliary muscle, like all muscles, has alength-tension relationship, the maximum force the ciliary muscle canapply decreases, as its length shortens with increasing age. This is theetiology of the age-related decline in accommodative amplitude thatresults in presbyopia. Any implant that increases radial compressioninternal to the capsule (directed outward), increases the equatoriallens diameter and decreases the amplitude of accommodation.

Thus, an IOL which is responsive to the natural accommodative mechanismof the human eye preferably possesses the following properties:

-   -   1. Does not apply a radial force directed outwards near the        equatorial plane of the capsule, so as not to work against        accommodation.    -   2. Possesses a centering mechanism largely based on volume of        the IOL relative to the volume of the natural capsule    -   3. Is resistant to gravitationally induced asymmetry, yet is        highly compliant    -   4. Possesses an internal structure that tends to stabilize the        shape of the IOL in an ellipse with an aspect ratio        approximately <0.6    -   5. The surface of the IOL follows, without relative motion,        changes in shape of the natural capsule    -   6. Possesses approximately the same modulus or less than the        capsule    -   7. Possesses a fixed index of refraction discontinuity relative        to the capsule    -   8. Possesses approximately the same water content as lens matter    -   9. Is naturally buoyant (same specific gravity as surrounding        tissue)    -   10. Provides a means to adjust the set point dioptric power        during implantation    -   11. Provides an accommodative dioptric range of 15 Diopters    -   12. Provides capsule filling lens volume    -   13. Requires minimal surgical disruption by being formed at the        implantation site    -   14. Has a minimized lens thickness        Requirements 12 and 14 appear to be contradictory, and it is        this contradiction that will be addressed presently. The focal        length of an implanted IOL can be calculated from

$\varphi = {\frac{1}{f} = {( {n - 1.33} )\lbrack {\frac{1}{R_{1}} - \frac{1}{R_{2}} + \frac{( {n - 1.33} )d}{{nR}_{1}R_{2}}} \rbrack}}$

Where f is the focal length of the lens,

-   -   n is the refractive index of the lens material,    -   R₁ is the radius of curvature of the lens surface closest to the        light source,    -   R₂ is the radius of curvature of the lens surface farthest from        the light source,    -   d is the thickness of the lens (the distance along the lens axis        between the two surface vertices).    -   Φ is the optical power in diopters if R is in meters.

The signs of the lens' radii of curvature indicate whether thecorresponding surfaces are convex or concave. The sign convention usedto represent this varies, but here if R₁ is positive the first surfaceis convex, and if R₁ is negative the surface is concave. The signs arereversed for the back surface of the lens: if R₂ is positive the surfaceis concave, and if R₂ is negative the surface is convex. If eitherradius is infinite, the corresponding surface is flat. With thisconvention the signs are determined by the shapes of the lens surfaces,and are independent of the direction in which light travels through thelens.

Making the simplifying assumption R1=−R2,

$\varphi = {\frac{1}{f} = {( {n - 1.33} )\lbrack {\frac{2}{R_{1}} - \frac{( {n - 1.33} )d}{{nR}_{1}^{2}}} \rbrack}}$

Then the second term

$\frac{( {n - 1.33} )d}{2{nR}_{1}^{2}}$

subtracts from the first, reducing the power of the optical system.Decreasing the radius of curvature, making the lens rounder, increasesthe second term much faster than the first term. The zero powercondition, ϕ=0, occurs when

${\frac{2}{R_{1}} - \frac{( {n - 1.33} )d}{{nR}_{1}^{2}}} = 0$Or $\frac{2{nR}_{1}}{( {n - 1.33} )} = d$

When the lens is a perfect sphere, R is about 4 mm and

$\frac{2n}{( {n - 1.33} )}$

is approximately 8, so d is approximately 8R. Accordingly, it is veryimportant that the IOL not be compressed equatorially. This is perhapsthe reason why the natural lens is always in tension with the suspensoryligament. Placing an equatorial ring inside a compliant IOL which is notsuspended within the capsule is not preferred because it would almostcertainly degrade accommodation range during ciliary contraction orbecome de-centered during ciliary dilation. An IOL which places anoutward radial force on the capsule, a lens configured like theCrystalens, would be predisposed to one or both of these limitations.

It is worth noting that d is 0 if the equator of the lens is notflattened at any point during accommodation (refer back to thedefinition of d). Suspension readily accomplishes this criterion for anyvolume of lens capable of fitting within the capsule, whereas apassively inserted bag-like IOL would suffer significant optical powerloss if the equatorial perimeter of the IOL were to sag away from theequator of the capsule, or otherwise not be actively suspended by thecapsule. Conversely, any inserted ring or bag thickening around theequator to keep the lens in contact with the capsule would resistaccommodation, or worse cause the equator to fold under accommodation.One solution is to glue or otherwise attach the bag-lens to the equatorof the capsule so that during all phases of accommodation the bag is intension. This would require the bag to be highly elastic.

It is instructive to consider the specific composition of the naturallens and capsule. Referring to FIG. 1C, the lens capsule 75 is a smooth,transparent basement membrane that completely surrounds the lens. Thecapsule is elastic and is composed of collagen. It is synthesized by thelens epithelium and its main components are Type IV collagen andsulfated glycosaminoglycans (GAGs). The capsule is very elastic and socauses the lens to assume a more globular shape when not under thetension of the zonular fibers, which connect the lens capsule to theciliary body. The capsule varies from 2-28 micrometers in thickness,being thickest near the equator 77 and thinnest near the anterior 79 andposterior 80 poles.

Referring now to FIGS. 1A and 1B, the lens fibers 70 form the bulk ofthe lens 54. They are long, thin, transparent cells, firmly packed, withdiameters typically between 4-7 micrometers and lengths of up to 12 mmlong. The lens fibers stretch lengthwise from the posterior to theanterior poles and, when cut horizontally, are arranged in concentriclayers 80 rather like the layers of an onion. If cut along the equator,it appears as a honeycomb 70. The middle of the fibers is at the equator60. The middle of each fiber lies in the equatorial plane. These tightlypacked layers of lens fibers are referred to as laminae 80. The lensfibers are linked together via gap junctions and interdigitations of thecells that resemble “ball and socket” forms. It is this later featurethat enables the fibers to be stretched in the axial direction withoutsagging in the equatorial plane. Thus, in order to enable a bag-like IOLone prefers the IOL to be filled with a series of elastic rodspreferring an extended length, the extended rod lengths chosen such thatthey are shaped to the radius of curvature achieved at the high powerextreme of the accommodative optical power spectrum while each rod inall accommodative states experiences approximately the same magnitude oftension-compression. To achieve this each rod needs to be articulatedlaterally with its neighboring rods. The rods must be suspended in afluid, incompressible medium. And the rod ends must be bonded to eitherthe natural capsule or a synthetic tightly fitting bag, such that theshape of the bag is substantially a function of the axial and lateralspring constants of the rods and their lateral pivoting connector. Thelateral pivoting connection must be both elastic and pivoting in orderto provide for equatorial diameter change that does not overly constrainlens axial lengthening.

Heretofore, a number of patents and publications have disclosed IOLdevices and other optical implant devices, the relevant portions ofwhich may be briefly summarized as follows.

U.S. Pat. Nos. 5,213,579 and 5,091,121 describe an intraocular lensincluding a balloon member formed of an elastomers and adapted to beinserted into a capsular bag of an eye, an optically transparent fluidwhich is injected into the balloon member so that the balloon memberexpands and fills the capsular bag, and a tube provided on the balloonmember and having a bore through which the optically transparent fluidis injected into the balloon member. The bore of the tube is filled withand closed by a gel filler. The fluid serving as a lens medium isinjected into the balloon member through the tube, with the gel fillerinhibiting leakage of the fluid from the balloon member.

U.S. Pat. No. 5,391,590 discloses an injectable intraocular lenses. Inone embodiment, such injectable compositions comprise polymer mixturesderived from the polymerization, for example, cross-linking, of curablecomponents in precursor mixtures. These precursor mixtures comprisecurable component comprising: (A) an unsaturation functional (vinylgroup-containing) polyorganosiloxane component, (B) an organosiliconcomponent including silicon-bonded hydride groups which react with theunsaturation functional groups included in (A) during thepolymerization, and (C) an effective amount of a platinum groupmetal-containing catalyst component; and a polymer component which issubstantially non-functional.

U.S. Pat. No. 6,613,343 relates to pre-polymerized compositionscomprising polysiloxanes suitable for the preparation of accommodatingintraocular lenses, having a specific gravity of greater than about 1.0,a refractive index suitable for restoring the refractive power of thenatural crystalline lens and a viscosity suitable for injection througha standard cannula.

U.S. Pat. No. 6,361,561 describes polysiloxanes suitable for thepreparation of intraocular lenses by a crosslinking reaction, having aspecific gravity of greater than about 1.0, a refractive index suitablefor restoring the refractive power of the natural crystalline lens and aviscosity suitable for injection through a standard cannula.

U.S. Pat. No. 3,947,401 discloses an intraocular lens assembly forincreased depth of focus and has a frame configured to vault posteriorlyin an eye and an optic attached thereto. Pressure from ciliary musclecontraction moves the optic anteriorly to focus the eye for near vision.U.S. Pat. No. 3,947,401 discloses a bulk polymerized, water insolublebut water swellable polymer of monomers comprising water solublemonoester of acrylic or methacrylic acid with a polyhydric alcohol; andglycidyl methacrylate, and/or glycidyl acrylate, and/or glycidylcrotonate. The polymer may be swelled in aqueous solution to provide atransparent hydrogel having excellent physical properties, and suitablein an ophthalmic lens.

U.S. Pat. No. 4,050,192 discloses a multifocal ophthalmic lens ofhomogeneous transparent optical material and method and apparatus forforming same, useful for the correction of the refractive error and theaccommodative insufficiency or absence of accommodation in presbyopiaand in aphakia, the lens characterized by having a unique variable frontsurface and a coacting spherical or toric back surface, said variablefront surface characterized by being geometrically and optically regularand continuous and having a pair of intersecting orthogonal principalplanes.

U.S. Pat. No. 5,073,021 discloses a dual focal length ophthalmic lensformed from a birefringent material with its fast and slow axesperpendicular to the user's visual axis. The dual focal property arisesdue to the differing indices of refraction of the birefringent materialfor light polarized parallel to the fast and slow axes. Light emanatingfrom far objects having one polarization and light emanating from nearobjects having the opposite polarization are both focused onto theuser's retina. Depending upon which object is being viewed, an in-focusand a blurred image appear simultaneously on the user's retina. Theability of the user's eye/brain system to distinguish between the twoimages provides bifocal action from a single lens.

U.S. Pat. No. 5,223,862 discloses an ophthalmic lens embodying anorganic plastic lens member having a refractive index of at least 1.56and being the cured product of a monomeric formulation. The formulationcontains a resin monomer base, a curing agent selected from aromaticanhydrides, aromatic diamines, thioamides and thioamines, and arefractive index enhancing additive selected from alkyl or aromaticdiols or thiols and transition metal alkoxides. The organic plastic lensmember may be an integral, monofocal lens, or a segment embedded in acavity in the front, convex surface of an organic plastic, major lensmember having a lesser refractive index. The latter may have a thin,inorganic glass lens member adhered to its front, convex surface toproduce a glass-plastic, laminated, multifocal lens structure.

U.S. Pat. No. 5,408,281 discloses a multifocal ophthalmic lens with aspiral-like pattern on its surface in an area overlying the cornea of awearer of the lens. The spiral-like pattern is capable of providing aplurality of different dioptric powers.

U.S. Pat. No. 5,690,953 discloses a soft hydrogel contact lens derivedfrom a crosslinked polymer made by reacting a hydrophilic monomer with across linking amount of a polyfunctional compound containing asaccharide residue.

U.S. Pat. No. 5,702,440 discloses a multifocal ophthalmic lens havingouter annular zones with vision correction powers less than a far visioncorrection power of the patient, is disclosed. These additional annularzones come into play, when the pupil size increases under dim lightingconditions, to thereby compensate for the near-vision powered annularzones. The net effect of the additional near vision annular zones andthe additional annular zones having power less than the far visioncorrection power is to shift the best quality image from in front of theretina to an area on the retina of the eye

U.S. Pat. No. 6,158,862 discloses a multifocal ophthalmic lens having adye or dyes that block the transmission of near UV and/or blue light.

U.S. Pat. No. 6,520,637 discloses an ophthalmic lens with a posteriorsurface and an anterior surface having a spherical central opticalcorrection zone, an aspheric intermediate zone, and a peripheral zone.

U.S. Pat. No. 6,682,194 discloses a progressive multifocal ophthalmiclens having a far vision region, an intermediate vision region and anear vision region, a main meridian of progression passing through saidthree regions, and a power addition equal to a difference in mean spherebetween a near vision region control point and a far vision regioncontrol point is provided.

U.S. Pat. No. 6,858,305 discloses an organic glass ophthalmic lenshaving an impact-resistant primer layer based on polyurethane latex andits manufacturing process.

U.S. Pat. No. 7,029,116 discloses an ophthalmic lens fornearsightedness, manufactured as a finished or semi-finished lens,lighter and thinner at the edges, with a wide visual field andcosmetically attractive, featuring a spherical centre and an asphericalperiphery, both asymmetrical to the lens optical centre and varying inwidth.

U.S. Pat. No. 7,192,138 discloses an ophthalmic lens with an opticalzone with a first corrective power range in a first region and a secondcorrective power range in an annular region surrounding the firstoptical zone.

U.S. Pat. No. 7,370,962 discloses an invention with a multifocalophthalmic lens that both corrects for the wearer's refractiveprescription and takes into account pupil size of a specific individualor of a population of individuals.

U.S. Pat. No. 7,404,638 discloses a method and apparatus for increasingthe depth of focus of the human eye is comprised of a lens body, anoptic in the lens body configured to produce light interference, and apinhole-like optical aperture substantially in the center of the optic.

U.S. Pat. No. 7,441,894 discloses a trifocal ophthalmic lens thatincludes an optic having at least one optical surface, and a pluralityof diffractive zones that are disposed on a portion of that surfaceabout an optical axis of the optic.

U.S. Pat. No. 7,559,949 discloses an injectable intraocular lens formedin situ.

U.S. Pat. No. RE34, 251 discloses a multifocal, especially bifocal,intraocular, artificial ophthalmic lens of transparent material, whoseoptical lens portion is divided into near range and far range zones and,each of which is disposed on the optical lens portion with approximatelyequal surface proportions and symmetrically with the lens axis.

U.S. Pat. No. 5,033,839 discloses a unifocal ophthalmic lens withpart-spherical concave and convex surfaces.

U.S. Pat. No. 5,106,180 discloses an ophthalmic lens with front and rearoptical surfaces, a central optical axis substantially perpendicular tothe lens and comprises a plurality of concentric, contiguous circularrefractive bands provided on at least one of the front and rear opticalsurfaces.

U.S. Pat. No. 5,311,223 discloses an ophthalmic lens with a polymercomposition composed of the reaction product of a hydrophilic monomerand an acyclic monomer is disclosed.

U.S. Pat. No. 5,517,260 discloses an ophthalmic lens including a firstzone located in a central portion of the ophthalmic lens such that acentral axis intersects the center of the first zone. The first zonehaving a spherical posterior surface for correcting distance vision. Theophthalmic lens further includes a second zone, positioned about theperiphery of the first zone, and having a posterior surface ofrevolution defined by rotating a portion of a spiral curve about acentral axis of the ophthalmic lens.

U.S. Pat. No. 5,699,142 discloses a multifocal ophthalmic lens includingan apodization zone with echelettes having a smoothly reduced stepheight to shift the energy balance from the near image to the distantimage and thus reduce the glare perceived when viewing a discrete,distant light source.

U.S. Pat. No. 6,145,987 discloses a multifocal ophthalmic lens withspherical aberration varying with the addition and the ametropia.

U.S. Pat. No. 6,196,685 discloses a method for fitting and designing anophthalmic lens for a presbyope that yields improved visual acuity ingeneral, and takes into account individual fitting characteristics.

U.S. Pat. No. 6,576,011 discloses a multifocal ophthalmic lens, havingouter annular zones with vision correction powers less than a far visioncorrection power of the patient, is disclosed. These additional annularzones come into play, when the pupil size increases under dim lightingconditions.

U.S. Pat. No. 6,802,606 discloses a progressive multifocal ophthalmiclens pair in which the dominant eye lens incorporates more distancevision correction than does the lens for the non-dominant eye.

U.S. Pat. No. 7,004,585 discloses a lens with an anterior surface and anopposite posterior surface, wherein the anterior surface includes avertical meridian, a horizontal meridian, and a central optical zonehaving at least a first optical zone for primary gaze, a second opticalzone for down-gaze and an optical blending zone between the first andsecond optical zones.

U.S. Pat. No. 7,073,906 discloses a multifocal ophthalmic lens with alens element having anterior and posterior surfaces with a centralaspherical refractive zone disposed on one of the anterior and posteriorsurfaces; and a diffractive bifocal zone disposed outside of theaspherical refractive zone.

U.S. Pat. No. 7,210,780 discloses a method for determination byoptimization of an ophthalmic lens for a wearer for whom a poweraddition has been prescribed.

U.S. Pat. No. 7,377,641 discloses a multifocal ophthalmic lens with onebase focus and at least one additional focus, capable of reducingaberrations of the eye for at least one of the foci after itsimplantation, comprising the steps of: (i) characterizing at least onecorneal surface as a mathematical model; (ii) calculating the resultingaberrations of said corneal surface(s) by employing said mathematicalmodel; (iii) modeling the multifocal ophthalmic lens such that a wavefront arriving from an optical system comprising said lens and said atleast one corneal surface obtains reduced aberrations for at least oneof the foci.

U.S. Pat. No. 7,427,134 discloses a multifocal ophthalmic lens with acomplex surface having a prism reference point, a fitting cross, aprogression meridian having a power addition greater than or equal to1.5 diopters.

U.S. Pat. No. 7,455,404 discloses an ophthalmic lens for providing aplurality of foci has an optic comprising an anterior surface, aposterior surface, and an optical axis. The optic has a first region anda second region. The first region has a refractive optical power andcomprises a multifocal phase plate for forming a first focus and asecond focus.

Most IOLs in use today are composed of a thin optic (usually less than1.0 mm at the thickest dimension) attached to haptics which center theIOL and keep it in place. Haptics apply radial or equatorial pressure tothe suspensory ligament, compromising accommodation. It is an object ofthe present invention to provide an IOL that does not require haptics tostay centered in the eye capsule.

The current thin optic of IOL's available prior to the presentapplication replace nature's 4.0-5.0 mm thick crystalline lens with amuch flatter lens (on the order of 1 mm in anterior-posteriorthickness). The flatness of the lens results in increases in the depthand volume of both the anterior chamber and the vitreous cavity. Thevitreous body consequently has more space in which to move, and thisinstability has been associated with an increased incidence of retinalbreaks and detachment. This problem is more significant if posteriorvitreous detachment has not yet occurred.

Multifocal lenses do provide functional “pseudo accommodation.” However,this optical goal of multifocality is achieved at the expense of otherimportant visual qualities: multifocal lenses create increased glare,and decreased contrast sensitivity and color discrimination. It isfurther an object of the present disclosure to provide an IOL havingimproved contrast sensitivity and color discrimination withoutundesirable glare.

Currently, the Crystalens IOL (Eyeonics, Inc., Aliso Viejo, Calif.) isthe only FDA-approved accommodative IOL. This lens is similar to atraditional IOL in that it has an optic and haptics. However, unlike thetraditional flat IOLs, the Crystalens has a movable haptic-opticjunction that functions like a hinge and theoretically producesaccommodation Like traditional multipiece IOLs, of course, theCrystalens induces posterior capsular opacification, which requirespost-operative Nd:YAG capsultomoties. This laser procedure creates anadditional expense and potential complications, such as an increasedrisk of retinal detachments. Finally, such destruction of the posteriorcapsule may hinder the accommodative ability of this IOL. It is furtheran object of the present invention to provide an IOL which does notdamage adjacent tissue.

Such conventional methods and systems have generally been consideredsatisfactory for their intended purpose. However, there is a need for acrystalline lens replacement with a close functional approximation ofthe healthy lens: a lens with varying dioptric power that is enclosedwithin the natural capsule. In this way, the ciliary muscles remaineffective. There is a need for an IOL responsive to the ciliary musclering, such that when the IOL is implanted the zonular fibers surroundingthe lens are not placed in a permanently relaxed state, allowing thelens to become more spherical than it would otherwise. The presentinvention provides a solution for these problems.

It is further an object of the present invention to replace the currenttechnology of IOLs that imitate a presbyopic lens with a new IOL thatimitates nature's accommodative lens. It is yet another object of thepresent invention to provide an injectable IOL to allow for aminimally-invasive limbal incision. Studies have shown that pressureexerted on the capsular bag reduces epithelial cell proliferation ormigration at the area of contact. (Assia EI, Castaneda VE, Legler UFC,et al. Studies on cataract surgery and intraocular lenses at the Centerfor Intraocular Lens Research. Ophthalmol Clin North Am 1991;4(2):251-266.) It is yet another object of the present invention toprovide an optic that will not rub against the posterior capsular bagand will not create opacification of the posterior lens capsule.

SUMMARY OF THE INVENTION

The subject invention is directed to a new and useful intraocular lensfor assisting the function of a human eye disposed within a body. Theintraocular lens includes an outer wall or bag which may be filled. Thebag may be compressed, such as by rolling, to a minimum diametersuitable for insertion into an incision at the limbus of the eye (wherethe cornea meets the sclera) and through a capsulorrhexis, a circularcentral opening in the anterior capsule of the crystalline lens.Optimally, the bag may be inflated within a space made within thecapsule formed by removing the lens fibers, and oriented such that theequator of the bag is adjacent the capsular equator. The bag may then bedeflated in preparation of receiving a liquid filling optical mediumwhich cures to a substantially solid state after entering the bag.Preferably, the filling material cures to form cross links between theanterior and posterior surfaces of the bag. This cross-linking providesinternal structure to the lens.

There is further provided an IOL for assisting the accommodativefunction of an eye disposed within a body having an outer wall, the IOLincluding an ellipsoid of revolution shape having an exterior wall, aninterior wall, an anterior pole, and a posterior pole; an equatorialmargin with an outer surface and an inner surface, an inner mediumjoined to said interior wall so as to form an incompressible volumebetween said anterior pole and posterior pole; and the inner mediumpreferably comprised of a fluid phase and a solid phase, the solid phaseapplying a variety of restorative forces on at least a portion of theouter wall of the IOL. The optional solid phase and liquid phasecombination may facilitate accommodation. Thus, if the filling materialwere 100% in the liquid phase, the amount of force required to alter andmaintain the shape of the lens is likely to be higher than if a portionof the lens is solid and only a portion of the filling is in the liquidphase and needs to be moved or reshaped to achieve accommodation. Thus,if a portion of the filling is solid, either as a result of beingpreformed prior to insertion or because that portion of the fillingmaterial solidifies in situ, and is surrounded by a liquid or gelmaterial which is more pliable than the solid phase, as the musclesadjust to change the shape of the lens the solid portion will remainintact while only the liquid or gel portion is deformed around the solidportion to adjust lens power.

There is further provided a method for assisting the function of a humaneye disposed within a body, including an outer wall and liquid fillingmedium, the method including a focal length assessment means; an IOLinsertion means; an IOL inflation means such that when the liquidfilling medium is delivered to the IOL disposed within the capsule of ahuman eye the focal length assessment means provides for real-timeassessment of the focal length of the IOL relative to the retina of theeye during filling. This method may be particularly useful where thelens is formed in situ in multiple “pours” that is, injecting a portionof the filling material, assessing the lens, and adding additionalfilling material in one or more additional injections until the desiredlens characteristics are achieved.

There is further provided a method for assisting the function of a humaneye disposed within a body, including an outer wall, the methodincluding the steps of partially filling an inflatable IOL lens disposedwithin the capsule of a human eye until the equatorial circumference ofthe IOL is in juxtaposition with the equatorial circumference of thecapsule; allowing the filling medium to cure to form a first halfdefining an equatorial plane within the IOL, introducing additionalfilling medium until the IOL is inflated to a desired curvature duringwhich time a focal length measurement means can be employed to determinethe proper final curvature of the IOL; allowing the additional fillingmedium to cure while the patient is in a recumbent position, anddisconnecting the filling means from said IOL.

The IOL described herein is advantageous because compared to otherdevices, it utilizes natural accommodation to precisely vary the opticalpower of the eye without damaging the tissue thereof, or the circulatingaqueous materials. In a preferred embodiment the IOL uses at least onein situ curing medium to ensure the IOL-eye system re-establishes theaccommodative mechanism so that the optical system of the patient canrespond to changes in spatial images and illumination; permitting thelens to be installed by a simple procedure that can be quicklyperformed. In addition, the IOL localizes in the natural capsule so asto minimize de-centering and accommodation loss; providing functionalperformance similar to a natural eye; and allowing volumetricaccommodation so that the ciliary muscle can control accommodation ofthe IOL. As a result, a greater variety of patients with lens diseasecan be provided with natural, responsive acuity, under a greater varietyof circumstances, including but not limited to, enhanced capacity foraccommodation, reduced glare, and extended or even permanentfunctionality because it utilizes a novel combination of solid andliquid phases to enhance the optical performance of the eye andestablish normal visual experience.

These and other features of the systems and methods of the subjectinvention will become more readily apparent to those skilled in the artfrom the following detailed description of the preferred embodimentstaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject inventionappertains will readily understand how to make and use the devices andmethods of the subject invention without undue experimentation,preferred embodiments thereof will be described in detail herein belowwith reference to certain figures, wherein:

FIG. 1A is a cut-away perspective view of the lens structure of thehuman eye;

FIG. 1B is a cross-sectional perspective view of a portion of the humaneye of FIG. 1A, showing the capsule, epithelial cell, and fiber layers;

FIG. 1C is a cross-sectional view of the lens of FIG. 1A, schematicallyshowing the wall thickness of the human lens capsule;

FIG. 1D cross-sectional view of an exemplary embodiment of an IOL of thepresent disclosure, showing the capsular interface, anterior pole shape,posterior pole shape, and an internal medium;

FIG. 2 is a schematic microscopic view of the IOL of FIG. 1D, showing afilling medium disposed in a capsular interface;

FIG. 3A is a cross-sectional view of the IOL of FIG. 1D, showing themechanism of cranial-caudal restorative forces;

FIG. 3B is a cross-sectional view of the IOL of FIG. 1D, showing themechanism of anterior-posterior restorative forces;

FIG. 4 is a cross-sectional view of an exemplary embodiment of an IOLconstructed in accordance with the present disclosure, showing acapsular interface that possesses internal structure;

FIG. 5A is a cross-sectional view of the IOL of FIG. 4, illustrating amethod of establishing the optical power set point;

FIG. 5B is a schematic view of an exemplary configuration forimplantation of a capsular interface in accordance with the presentdisclosure;

FIG. 5C is a schematic view of another exemplary configuration forimplantation of a capsular interface in accordance with the presentdisclosure;

FIG. 5D is a schematic elevation view of yet another exemplaryconfiguration for implantation of a capsular interface in accordancewith the present disclosure;

FIG. 5E is a schematic perspective view of the configuration forimplantation of a capsular interface shown in FIG. 5D;

FIG. 5F is cross-sectional view of a capsular interface in accordancewith the present disclosure, showing implantation of the capsularinterface;

FIG. 5G is a cross-sectional perspective view of an exemplary sealingconfiguration decoupled from a localization function in accordance withthe present disclosure;

FIG. 5H is a cross-sectional perspective view of the sealingconfiguration of FIG. 5G, showing the function of the sealingconfiguration when a delivery catheter is inserted into the capsularinterface; and

FIG. 6 is a plan view schematically showing exemplary features forlocalizing an IOL in accordance with the present disclosure within thenatural capsule such that the IOL is suspended rather than compressed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like referencenumerals identify similar structural features or aspects of the subjectinvention. For purposes of explanation and illustration, and notlimitation, a partial view of an exemplary embodiment of an intraocularlens (IOL) in accordance with the invention is shown in FIG. 1D and isdesignated generally by reference character 100. Other embodiments ofIOLs in accordance with the invention, or aspects thereof, are providedin FIGS. 2-6, as will be described. The system of the invention can beused, for example, to provide a crystalline lens replacement with aclose functional approximation to a healthy lens.

This description begins with a description of particular embodiments ofIOL devices, then attention will be directed to description ofparticular methods of implantation of the IOL device, and finally novelfeatures will be described with respect to their benefit and utility inuse.

IOL Device Example 1

Referring to FIG. 1D, an IOL 100 is comprised of a capsular interface102, an anterior pole shape 104, a posterior pole shape 106, and aninternal medium 108. The internal medium 108 is further comprised ofanterior side 110 and posterior side 112. IOL 100 has an equatorialplane 114 which is co-planar with the interface between anterior side110 and posterior side 112. The index of refraction of anterior side 110is substantially equivalent to the index of refraction of posterior side112. The capsular interface 102 possesses internal side 116 and externalside 118. The intersection of the equatorial plane 114 with the capsularinterface 102 is the equatorial circumference 120 of the capsularinterface 102. Disposed posteriorly of the equatorial circumference 120on the external side 118 are localization areas 122. The localizationareas 122 adhere to the natural capsule, helping to center the IOLwithin the capsule and decreasing relative movement between the IOL andthe capsule. This connects the IOL and the capsule to minimize theattachment of the natural lens to the capsule. The width 124 oflocalization areas 122 can range from 100 micrometers to 2 millimeters.

Referring now to FIG. 2, a magnified view of the internal medium 108residing between the anterior 202 and posterior 204 walls of thecapsular interface 102 is shown. In the preferred case, internal medium108 is constructed of anterior side 110 and posterior side 112,alternatively the medium 108 is introduced into the capsular interface102 all at once in a liquid state and cured to a substantially solidstate in one step. The solidified polymer comprising 110 and 112preferably is comprised of an aqueous phase 206 and a solid phase 208,wherein the solid phase 208 is a polymeric network with a select degreeof cross linking. Depicted in FIG. 2 is a solid phase 208 with three-armfunctionality 210 comprising monomeric units 212. These three-armedmonomers 212 form extended networks when they polymerize within capsularinterface 102. The external side 118 of capsular interface 102 is smoothand resists tissue ingrowth. The internal side 116 of capsular interface102 is bonded with a thin layer of polymer active substance 214. Duringpolymerization the monomers 212 nearest internal side 116 tend to haveone of their arms 211 bond to polymer active substance 214. Theremaining arms 210 polymerize to other arms 210 of other monomers 212forming polymeric chains 216 anchored to internal side 116. Still othermonomers 218 away from internal side 116 form polymeric chains 220 withno anchor to internal side 116. Polymeric chains 216 and 220 arelaterally joined by a roughly perpendicular network of arms 222. Thereare then free ends 224 at the equatorial plane 114. If a second layer ispoured, we again have bonds 226 to the opposite internal side 110 andfree polymeric chains 228. During the second layer polymerization, someof the polymeric chain ends 230 in the second polymerizing layer joinwith free ends 224, but not all. Thus, anterior side 110 is more looselycoupled to posterior side 112, than the coupling within anterior side110 and posterior side 112. Thus whatever shape was achieved for theanterior side 110 is somewhat decoupled from the shape achieved for theposterior side 112. In a single pour methodology the anterior side 110is more strongly coupled to posterior side 112, since polymeric chainsare in general longer and there are almost no free ends near theequatorial plane 114. In either case there will be polymeric chains 232connecting the anterior side 110 to the posterior side 112 and freepolymeric chains 234 connecting neither side 110 nor 112.

Referring now to FIGS. 3A and 3B, the polymeric structure of the fullypolymerized internal medium 300 is shown. In one instance, FIG. 3A, acranial-to-caudal force 302 is applied in representation of anapproximate gravitational force. The distensible polymeric chains inbulk resist cranial-to-caudal dilation by supplyinganterior-to-posterior restorative forces 304. Anterior-to-posteriorforces 304 places tension on lateral arms 222 which causes the angle 306between representative lateral arm 308 and representative axialpolymeric chain 310 to decrease to angle 312 with the lateral armposition 314 and new polymeric chain position 316. Thus, while theaction of gravity is unidirectional, the degree of cranial-to-caudalshortening is symmetric about axial centerline 318 and the degree ofanterior-to-posterior dilation is proportionally symmetric about theequatorial plane 114. In FIG. 3B, an anterior-to-posterior force 320 isapplied. This is the force applied by the capsular interface 102 to theinternal medium 300 when the capsular interface is suspended within thecapsule. Force 320 causes distensible polymeric chains in bulk to resistcranial-to-caudal dilation by supplying cranial-to-caudal restorativeforces 322. Cranial-to-caudal forces 322 places tension on lateral arms222 which causes the angle 324 between representative lateral arm 326and representative axial polymeric chain 328 to increase to angle 330with new lateral arm position 332 and new polymeric chain position 334.FIGS. 3A and 3B describe a set of restorative forces designed to keepthe IOL in a preferred ellipsoidal shape under the action of gravity,while providing for accommodative changes anterior and posterior radiiof curvature. Generally speaking, the concept of having both a solidphase and a liquid or lower modulus phase is intended to minimize thevolume of the filling that must be affected through muscular action inorder to achieve accommodation. It will be appreciated that such amultiple phase configuration may be achieved by: (1) inserting thecapsular bag into the prepared space, inserting a preformed solidportion into the capsular bag, positioning the solid portion within thebag, and injecting one or more “pours” of filling material around thesolid portion; (2) inserting the capsular bag into the prepared spacewith the solid portion pre-attached to the inside of the capsular bag,and filling around the solid portion within the bag until the desiredoptical properties are achieved; or (3) inserting the capsular bag intothe prepared space, injecting a first material into the bag to form themore solid portion of the filling within the bag, possibly adhered to aninterior surface of the bag, and injecting one or more pours ofadditional material around the solid portion to provide the area oflower modulus and greater deformability around the solid portion. It iscontemplated that providing multiple phases and/or multiple injectionsof similar materials may provide greater flexibility to adjust index ofrefraction between materials and lens power during accommodation.

IOL Device Example 2

In some cases a patient's accommodative capacity is markedly diminishedand cannot be enhanced by providing an improved accommodative gain(optical power range) or set point (optical power mean). In this case,it may be necessary to interpose within the capsular interface a solidinflexible optic. While the scope of this invention includes combiningthe accommodative power of shape changes in the capsular interface withanterior-posterior translations of an optic, it is generally the casethat acuity and contrast is superior in the instance of the fewestrefractive index discontinuities. In order for the capsular shape toincrease total eye optical power it would be necessary for the index ofrefraction inside the capsular interface to be somewhat higher than theindex of refraction of the tissue anterior or posterior to the capsularinterface. Accordingly, it is preferred the capsular bag be filled witha bi-phasic flowable medium with a refractive index close to that of thesurrounding tissue.

Referring now to FIG. 4, an IOL 400 is comprised of a capsular interface102, an anterior pole shape 104, a posterior pole shape 106, and aninternal flowable medium 402. The internal medium 402 is furthercomprised of anterior side 110 and posterior side 112. IOL 400 has anequatorial plane 424 which is co-planar with the interface betweenanterior side 110 and posterior side 112. The index of refraction ofanterior side 110 is substantially equivalent to the index of refractionof posterior side 112 and substantially equivalent to the surroundingtissue. The capsular interface 102 possesses internal side 116 andexternal side 118. The intersection of the equatorial plane 424 with thecapsular interface 102 defines the equatorial circumference 120 of thecapsular interface 102. Disposed on the equatorial circumference 120 onthe external side 118 is located localization area 122 runningcircumferentially along the equatorial circumference 120 of capsularinterface 102. The localization areas 122 adhere to the natural capsule,helping to center the IOL within the capsule and decreasing relativemovement between the IOL and the capsule. This connects the IOL and thecapsule to minimize the attachment of the natural lens to the capsule.The width 124 of localization areas 122 can range from 100 micrometersto 2 millimeters. Additionally there is cranial pole 404 and caudal pole406. On the internal side 116 of the cranial pole 404 is attached astrip of flexible, optically clear biocompatible material 408, the otherside of which is attached to the internal side 116 of the caudal pole406. Preferably, internal strip 408 and capsular interface 102 are asingle molded or cast part. The connections between internal strip 408and internal side 116 may be radiused 409 to avoid the intersection ofperpendicular surfaces for improve durability. The modulus of the strip408 and capsular interface 102 are between 0.1 and 2 MPa. Located nearthe center of strip 408 is a circular cutout 410 into which are bonded aconventional rigid optic 412 (not shown to scale). In order to maintainthe orthogonal relation between the equatorial plane of the IOL 414 andthe anterior-posterior axis of the eye 416, strip 408 contains twopreferential bend points 418 on either side of optic 412. In addition,it is preferred but not necessary that distal segments 420 adjacentpoles 404 be more flexible than central segment 422. Thus when theequatorial diameter 424 of the capsular interface 102 decreases 426 theangle 428 increases 430 resulting in translation of rigid optic 412along anterior-posterior axis 416 such that angle 414 remainsapproximately normal throughout the potential range of translation Inthis way the optic shifts forward and the power of the lens increases topermit focused viewing of near objects. While the rigid optic 412 may bebiased posteriorly as shown, it may also be biased anteriorly. Thus anIOL of this construction will typically have two optical power setpoints which are selectable during implantation. The length of strip 408must be adequately long such that throughout the range of accommodationthe position of the rigid optic 412 never crosses equatorial diameter424. The case where rigid optic 412 crosses equatorial diameter 424 atsome point in the accommodation range is addressed in the subsequentexample

Referring now to FIG. 5A, a labio-lingual view 500 of the internalmedium 502 residing between the anterior 202 and posterior 204 walls ofthe capsular interface 102 is shown. In the preferred case, internalmedium 502 is constructed of anterior side 504 and posterior side 506,where the thickness 508 of the posterior side 506 is less than thethickness 510 of the anterior side 504. The cured yet flowable polymercomprising 504 and 506 is comprised of an aqueous phase 206 and a solidphase 208, wherein the solid phase 208 is a polymeric network withselectable degree of cross linking. The specific weight of strip 408 isless than the specific weight of the internal medium 502 prior togelation such that the optic 412 floats on the surface of posterior side506 prior to gelation. The selection of thicknesses 508 and 510establishes the optical power set point of optic 412 and provides for invivo assessment of the focal length relative to the retina of the eye.Optic 412 is able to translate in response to a physiologic change inciliary muscle tension due to the flowability of internal medium 502around strip 408. It should be understood the solid inflexible optic 412is an optional feature, and that the strip 408 may possess refractive orgeometric properties along a substantial portion of it length thatachieve an enhanced accommodative effect. Additionally, the inflexibleoptic 412 may be a localized geometric form impressed into strip 408such that the entire strip is of one material.

IOL Device Example 3

In this example, for illustrative purposes figures of Example 2 will bereused since the features that differentiate Example 3 over Example 2are based on dimensional differences and not structural difference.

In some cases a patient's accommodative capacity is absent and cannot beenhanced by providing an improved accommodative gain (optical powerrange) or set point (optical power mean). In this case, the internaloptic 412 and strip 408 can be configured within capsular interface 102to achieve a bistable state. The bistable state is achieved when theoptic 402 can translate through the equatorial diameter 424. In thiscase, finger pressure or flexing of muscles around the eye can allow thepatient to select between an anterior biased position of optic 412 and aposterior biased position of optic 412. Thus, for the fixedaccommodative state of the patient's eye, there are two minimum energyconfigurations of the strip 408 within the capsular interface 102. Thesetwo minimum energy states correspond to near- and far-sightedaccommodations of the optical power of the eye. The difference indioptric power between these two accommodative states is a function ofthe length of the strip 408.

While the scope of this invention includes combining the accommodativepower of shape changes in the capsular interface with anterior-posteriortranslations of an optic, it is generally the case that acuity andcontrast is superior in the instance of the fewest refractive indexdiscontinuities. In the present case the eye has no naturalaccommodative power, accordingly it is preferred the capsular bag befilled with a bi-phasic flowable medium with a refractive index close tothat of the surrounding tissue.

Referring now to FIG. 4, an IOL 400 is comprised of a capsular interface102, an anterior pole shape 104, a posterior pole shape 106, and aninternal flowable medium 402. The internal medium 402 is furthercomprised of anterior side 110 and posterior side 112. IOL 400 has anequatorial plane 114 which is co-planar with the interface betweenanterior side 110 and posterior side 112. The index of refraction ofanterior side 110 is substantially equivalent to the index of refractionof posterior side 112 and substantially equivalent to the surroundingtissue. The capsular interface 102 possesses internal side 116 andexternal side 118. The intersection of the equatorial plane 114 with thecapsular interface 102 is the equatorial circumference 120 of thecapsular interface 102. The localization areas 122 adhere to the naturalcapsule, helping to center the IOL within the capsule and decreasingrelative movement between the IOL and the capsule. This connects the IOLand the capsule to minimize the attachment of the natural lens to thecapsule. The width 124 of localization areas 122 can range from 100micrometers to 2 millimeters.

Additionally there is cranial pole 404 and caudal pole 406. On theinternal side 116 of the cranial pole 404 is attached a strip offlexible, optically clear biocompatible plastic 408, the other side ofwhich is attached to the internal side 116 of the caudal pole 406.Preferably, internal strip 408 and capsular interface 102 are a singlemolded or cast part. The connections between internal strip 408 andinternal side 116 may be radiused to avoid the intersection ofperpendicular surfaces for improve durability. The modulus of the strip408 and capsular interface 102 are between 0.5 and 5 MPa. Located nearthe center of strip 408 is a circular cutout 410 into which are bonded aconventional rigid optic 412. In order to maintain the orthogonalrelation 414 between the equatorial plane of the IOL and theanterior-posterior axis of the eye 416, strip 408 contains twopreferential bend points 418. In addition, it is preferred but notnecessary that distal segments 420 be more flexible than central segment422. Thus when a pressure is applied by the conscious flexing of facialmuscles of the placement of the finger over the eye lid in either acranial or lateral aspect, the equatorial diameter 424 of the capsularinterface 102 changes 426 the angle 428 changes 430 resulting intranslation of rigid optic 412 along anterior-posterior axis 416 suchthat angle 414 remains approximately normal throughout the potentialrange of translation. The direction of angle changes 428 and 430 dependson the prior state of strip 408. Therefore, if the strip 408 is in theanterior position pressure placed peri-optically causes strip 408 to bedisplaced further anteriorly and the rebound effect of removing theexternal pressure causes strip 408 to pass through equatorial plane 414and is carried to the second energy minima in the posterior position.Conversely, if the strip is in the posterior position pressure placedperi-optically causes strip 408 to be displaced further posteriorly andthe rebound effect of removing the external pressure causes the strip408 to pass through equatorial plane 414 and is carried to the secondenergy minima on the anterior position. In this way a patient canreadily alternate between near and far-sighted accommodation. It isclear from this mechanism that the potential energy placed in strip 408during hyper-anterior or hyper-posterior extension of strip 408 must besufficient to carry strip 408 through the potential energy barrierpresented by the equatorial strip position. Therefore, the modulus orthe overall elasticity of the flexing mechanism built into strip 408determines the potential energy of the hyper-extension position governedby Hooke's Law. Ideally, one selects a flexural modulus that providesfor the desired hyper-extension with a minimal amount of externalpressure, but requires a sufficient pressure such that the position ofstrip 408 is not oscillating between anterior and posterior positionsduring normal eye movement.

It may also be desirable to bias the strip 408 to a positioncorresponding to near or far-sightedness, typically the far-sightedposition is chosen. While the rigid optic 412 may be biased posteriorlyas shown, it may also be biased anteriorly. Thus an IOL of thisconstruction will typically have two optical power set points which areselectable during implantation.

Referring now to FIG. 5A, a labio-lingual view 500 of the internalmedium 502 residing between the anterior 202 and posterior 204 walls ofthe capsular interface 102 is shown. In the preferred case, internalmedium 502 is constructed of anterior side 504 and posterior side 506,where the thickness 508 of the posterior side 506 is different from thethickness 510 of the anterior side 504. The solidified yet flowablepolymer comprising 504 and 506 is comprised of an aqueous phase 206 anda solid phase 208, wherein the solid phase 208 is a polymeric networkwith selectable degree of cross linking. The specific weight of strip408 is less than the specific weight of the internal medium 502 prior togelation such that the optic 412 floats on the surface of posterior side506 prior to gelation. The selection of thicknesses 508 and 510establishes the optical power set point of optic 412 and provides for invivo assessment of the focal length relative to the retina of the eye.Optic 412 is able to translate in response to an external change inocular tension due to the flowability of internal medium 302 aroundstrip 408. It should be understood the solid inflexible optic 412 is anoptional feature, and that the strip 408 may possess refractive orgeometric properties along a substantial portion of it length thatachieve an enhanced accommodative effect. Additionally, the inflexibleoptic 412 may be a localized geometric form impressed into strip 408such that the entire strip is of one material.

IOL Device Filling Medium Example 4

In this case the capsular interface must provide structural rigiditysufficient to retain the shape of the capsular interface under differentorientations with respect to gravity. In this embodiment the patientwill need a relatively robust accommodative power to overcome theincreased rigidity of the capsular interface, which will inherentlyoppose accommodative change. However, removal of an aged and stiffenedlens may be sufficient to augment the accommodative aspect of the eye.In the case where the filling medium is saline, then the refractiveindex of the capsular bag must be chosen to mimic the power of thenatural crystalline lens. Alternatively, if a nonstructural medium suchas glycerin or hyaluronic acid is used the index of refraction of thecapsular interface preferably matches that of the filling medium.

Maximum accommodative range is achieved when the filling mediumpossesses structure that mimics the natural eye. Distribution ofstructural integrity over the entire implant and not relying on thecapsular interface to provide form reduces the required modulus of thecapsular interface. A gel that retains its shape in a gravitationalfield does not require a stiff capsular interface. The differencebetween the modulus of the implant and the modulus of the naturalcapsule is a primary stimulus to posterior capsule opacification.Furthermore, rigid elastomers tend to be more hydrophobic than tissue,and difference in hydrophobicity is known to cause chronic inflammation.

Preferentially, the filling medium is a liquid in order to minimizedelivery catheter cross section. In order to meet the dual requirementsof a fluid injectable and a structure filling medium the filling mediumpreferentially changes state when implanted in a body. More preferredare filling agents that are capable of cross linking in the body. Morepreferred still, are prepolymers with two principle directions of chainextension so that a three dimensional rather than linear polymericnetwork is formed. One can align the polymerization direction relativeto the optical axis by coating the inner surfaces of the capsularinterface with a compound known to polymerize with the filling medium.The primary chains provide anterior-posterior stabilization, while theside chains provide cranial-caudal stability.

Ideally, the filling medium is permanent and retains good opticalqualities after implantation. Representative synthetic, biodegradable(but permanent when implanted in a sealed capsular interface)polymerizing systems include: poly(amides) such as poly(amino acids) andpoly(peptides); poly(esters) such as poly(lactic acid), poly(glycolicacid), poly(lactic-co-glycolic acid), and poly(caprolactone);poly(anhydrides); poly(orthoesters); poly(carbonates); and chemicalderivatives thereof e.g., substitutions, additions of chemical groups,for example, alkyl, alkylene, hydroxylations, oxidations, and othermodifications routinely made by those skilled in the art, copolymers andmixtures thereof. Representative synthetic, non-degradable polymerizingsystems include: poly(ethers) such as poly(ethylene oxide),poly(ethylene glycol), copolymers of these and poly(tetramethyleneoxide); vinyl polymers—poly(acrylates) and poly(methacrylates) such asmethyl, ethyl, other alkyl, hydroxyethyl methacrylate, acrylic andmethacrylic acids, and others such as poly(vinyl alcohol), poly(vinylpyrolidone), and poly(vinyl acetate); poly(urethanes); cellulose and itsderivatives such as alkyl, hydroxyalkyl, ethers, esters, nitrocellulose,and various cellulose acetates; poly(siloxanes); and any chemicalderivatives thereof e.g., substitutions, additions of chemical groups,for example, alkyl, alkylene, hydroxylations, oxidations, and othermodifications routinely made by those skilled in the art, copolymers andmixtures thereof.

Prepolymers of polyurethane provide durability and enhancedbiocompatibility due to their tissue-like hydrophilicity, especiallyamong the polyurea polyurethane systems. All polyurethanes aresynthesized using isocyanates or their associated amines. Thesecompounds are classed as aromatic or aliphatic. Aromatic polyurethanestend to yellow when implanted in the body, although the use ofanti-oxidants can diminish this tendency. It is preferred to usealiphatic isocyanates or amines because they do not yellow in the body.They are typically less stable than their aromatic counter-parts, butthis is not a great concern since the filling medium is enclosed in thecapsular interface.

Ideally, the prepolymer is mixed outside the body with polymerizationinitiators. In polyurea systems the initiator can be water. However, theaction of water is to convert isocyanate functional groups in theprepolymer to amines. A byproduct of this reaction is the release of gasphase carbon dioxide. Although there are known carbon dioxide absorbers,their action is generally too slow to prevent the formation ofinclusions in the polymerizing mass. Entrapped gas in the implant willcreate dispersion, which will dramatically decrease acuity. It istherefore preferred that the filling medium be a mixture of polymerswith isocyanate end groups and polymers with amine end groups. Since thereaction between isocyanates and amines is much faster than the two stepreaction of converting isocyanates to amine and then reacting theresulting amines with other isocyanatyes in the mixture, the reductionin cure time will help compensate for the generally slower reactingaliphatic isocyanates. In addition, biocompatible catalysts of tin ororganic catalysts or combinations of these can be used to furtherincrease the rate of reaction. Optimally, the mixture achieve a cohesivestate within about 5 minutes of mixing the initiator with theprepolymer. Preferably, a faster reaction with a reaction time between 1and 3 minutes is provided. Faster reactions are not preferred, and makedelivery problematic. Catalysts do not change the total amount of energyliberated in a chemical reaction, but they do change the rate at whichthe total energy is released. In biological systems, heat energy isgenerally carried away by the surrounding tissue. It is temperature andnot heat energy that is destructive, and typically tissue damage occursat about 50 degrees Celsius. Therefore, it is preferred that thecatalysts be chosen, if one is needed, such that the rate of reactiondoes not result in an elevation of tissue temperature above 50 degreesCelsius.

An example of a prepolymer system which achieves the aims of thisinvention consists of two parts: an isocyanate functionalized prepolymerliquid and an amine-catalyst initiator liquid, which when mixed rapidlyforms an optically clear and colorless gel. Preferably, the molecularweight of the isocyanate functionalized prepolymer is above 10,000Dalton, and more preferably above 15,000 Dalton. The base polymer can bedimethylsiloxane ethylene oxide block copolymer, for example PEG-113dimethicone (Meryer Chemical, China). These are linear chains ofcopolymer with 2 pendant OH groups with total molecular weight ofapproximately 9000 Dalton. In order to form the prepolymer, thedimethylsiloxane ethylene oxide block copolymer is reacted withisophorone diisocyanate (an aliphatic isocyanate) in sufficientquantities to ensure encapping of the dimethylsiloxane ethylene oxideblock copolymer without significant chain extension. The isocyanatefunctionalized dimethylsiloxane ethylene oxide block copolymer istrimerized with trimethylolpropane, which occurs spontaneously. Theresult is the prepolymer fraction Part A. The initiator, Part B, issimply a mixture of potassium octoate catalyst (Dabco-T45, Air Products,USA), isophorone diamine, and water. Shelf life may be improved byadding the water fraction peri-operatively. The following is a processfor preparing Parts A and B.

Part A: Place a 100 g of PEG-113 dimethicone in a heated and coveredreaction vessel fitted with an externally controlled stir rod. Circulatedry argon or nitrogen gas over the PEG-113 dimethicone and stir at 100revolutions per minute, or at a rate where a vortex is present but gasis not entrapped in the stirred liquid. Heat to 60 degrees Celsius whilestirring, and continue until the water content of the PEG-113dimethicone is less than 300 ppm. Then add 4.24 g of isophoronediisocyanate and continue at 60 degrees Celsius until the % NCO drops bygreater than 60% from the initial introduction of the isophoronediisocyanate to the PEG-113 dimethicone. Then add 0.61 g of trimethylolpropane and continue at 60 degrees Celsius while monitoring the heatoutput from the reaction. When the heat output is less than 4.5kilocalories per hour, continue to stir and heat for 2 more hours andthen cool and decant into a dry glass container and cap with a head ofdry gas.

Part B: Mix in a dry vessel 1.1 grams of isophrone diamine with 0.65 gof potassium octuate catalyst Dabco-T45 and 100 g of water. Mix for onehour and decant into a sealed glass container.

In the preparation of the filling medium equal parts of Part A and PartB are mixed between syringes until fully suspended. The preparation isready to be implanted and will typically gel within 3 minutes at bodytemperature.

IOL Device Delivery Features Example 5

Device delivery requires 3 features: a) a minimal cross sectionimplantation device suitable for delivering the capsular interfacethrough a hole no larger than 3 mm in diameter, b) an implantationdevice suitable for delivering the filling medium in a fluid statecomprising a sealing mechanism to prevent extrusion of the solidifiedfilling medium, and c) an implantation device which when deployed infilling the capsular interface, causes the capsular interface toseparate from the implantation device in a way that minimizes thelikelihood of capsular disruption.

Referring to FIG. 5B, a configuration 1000 of the capsular interface1002 relative to the delivery end of the catheter 1004 is shown. Thecapsular interface comprises internal volume 1006 (cross hatch) andexternal surface 1008. The capsular interface 1002 is rolled back uponthe catheter 1004 causing the external surface 1008 to form an annularenveloping surface around the catheter 1004. The diameter 1010 of thecombined external surface 1008 and catheter 1004 is less than 3 mm. Thecapsular interface 1002 is localized on catheter 1004 by means of anannular port 1012 which is stretched around the external surface tip1014 of catheter 1004. The internal volume 1006 is fluidically connectedto lumen 1016 of catheter 1004. Around the perimeter of opening 1012 thecapsular interface 1002 is thicker and in the shape of a ring 1018 suchthat ring 1018 grips catheter tip 1014.

Alternatively, FIG. 5C shows a different configuration 1050 forretaining capsular interface 1002 to catheter 1004. Here, capsularinterface ring 1018 is not stretched around external surface tip 1014.Juxtaposed between capsular interface external surface 1008 and externalsurface tip 1014 is tacky film 1052. The adhesive strength between theexternal surface of the capsular interface 1008 and external cathetertip 1014 provided by tacky film 1052 is sufficient to open ring 1018when fluidic pressure is applied via lumen 1016 such that lumen 1016 isfluidically connected to capsular interface internal volume 1006 withoutfluid leaking between the external surface 1008 and external cathetersurface 1014.

For both configurations 1000 and 1050, capsular interface annular ring1018 is capable of maintaining a fluid seal after catheter 1004 isdetached from capsular interface 1002. The fluid seal is achieved inconfiguration 1000 by pulling catheter 1004 away from capsular interface1002 such that annular ring 1018 slides off catheter tip 1014. The fluidseal is achieved in configuration 1050 as soon as fluidic pressure inlumen 1016 is reduced to ambient.

A third design 1100 for removing the fluidic connection between capsularinterface 1002 and catheter lumen 1016 and fluidically sealing capsularinterface 1002 is shown in FIGS. 5D and 5E. The catheter 1004 resides ina small pocket 1102 in capsular interface 1002. Pocket 1102 is comprisedof leading edge 1104 and trailing edge 1106 such that the wall ofcapsular interface 1002 forms overlap region 1108. The leading edge 1104is bonded to external capsular interface surface 1008 along bond line1110 and is not bonded along port opening 1112. When catheter 1004 isinserted into port opening 1112 (as shown) port opening 1112 isfluidically sealed to catheter 1004 and capsular interface 1002 islocalized on catheter 1004. Catheter lumen 1016 is fluidically connectedto capsular interface internal volume 1006. While catheter 1004 isinserted in port opening 1112 edge 1112 undergoes strain. When catheter1004 is removed from capsular interface 1002 edge 1112 fluidically sealsagainst external capsular interface surface 1008 and overlap region1108. To augment this sealing action overlap region 1108 may be coatedwith a material which will bond to the filling medium such that theentire overlap region 1108 is bonded.

The configuration of the capsular interface 1002 in design 1100 isdifferent from the configuration depicted in configuration 1000 and1050. In 1100 the capsular interface 1002 is wrapped around catheter1004 obtaining a cross sectional diameter of less than 3 mm.

Referring now to FIG. 5F, the catheter 1004 and capsular interface 1002are shown disposed within a human eye 1150. The principle landmarks ofthe eye 1150 are the cornea 1152, iris 1154 and capsule 1156. Forconfigurations 1000 and 1050 the capsular interface 1002 rolls offcatheter 1004 filling the posterior region of the capsule 1156 first.This configuration for inflating the capsular interface 1002 placesminimal pressure on the anterior region of capsule 1156. A hole must bemade in the capsule 1156 in order to extract the native lens and insertcatheter 1004. This capsulotomy is generally made with a capsulorrhexisprocedure by making a cut in the anterior surface of capsule 1156,tearing the central free flap in a circular motion to peel a continuouscircular tear in the anterior capsule. The present configurationprovides a means for inflating the capsular interface 1002 with minimalstress placed on the anterior surface of the capsule 1156.

For configuration 1100, the capsular interface 1002 does not roll offthe tip of catheter 1004 but unwinds in circumferential fashion. Thisconfiguration may be preferred by some clinicians since the deploymentof the capsular interface 1002 may be accomplished without inflating thecapsular interface 1002 by rotating catheter 1004. It should be apparentthat either configuration of capsular interface 1002 relative tocatheter 1004 is adaptable for any of the aforementioned three sealingconfigurations.

The annular ring 1018 of configuration 1000 and 1050 is designed tofluidically seal when the annular ring 1018 is disconnected fromcatheter 1004. The amount of strain required to achieve this feature maycreate enough force between annular ring 1018 and catheter 1004 that forsome capsular interface materials it may be difficult to detach catheter1004 from capsular interface 1002.

Alternatively, the localization function of annular ring 1018 may bedecoupled from the sealing function as shown in configuration 1200. FIG.5G depicts capsular interface 1002 as it would look in configurations1000 or 1050. The primary difference between configurations 1000 and1050 and the depicted configuration 1200 is that annular ring 1202 is ina normally open position with diameter 1204 slightly less than the outerdiameter of the mating catheter. Within diameter 1204 is tri-leafletvalve 1206. The number of leaflets is generally unimportant, but may bemade greater to achieve a lower resistance to decoupling betweencatheter 1004 and capsular interface 1002. When capsular interface 1208is decoupled from a catheter valve 1206 is closed.

The action of the tri-leaflet valve 1250 when catheter 1252 (solid) isinserted in capsular interface 1208 (dashed) is shown in FIG. 5H.Catheter 1252 is inserted into annular ring 1202 pushing apart leaflets1254 and stretching annular ring 1202. Catheter lumen 1256 isfluidically connected to capsular interface 1208 and catheter 1252 isfluidically sealed to annular ring 1202.

IOL Pre-Operative Method Example 6

This example concerns pre-operative accommodation determination of thepatient's eye and set point selection of the IOL of the presentinvention. Methods of accommodation assessment are known in the field,and must be performed when the eye is not pharmaceutically disposed to aparticular accommodative state. This information is useful in selectingthe IOL set point, accommodative gain, and accommodative range. Theselection of the set point is done best in consideration of these andother IOL features.

The set point can be set for a near or far-sighted accommodative state,usually a far sighted accommodative state corresponding to a relaxedstate of the ciliary muscles. However, the normal state of a pathologiceye may be a better set point selection. The set point is the opticalpower of the eye in the desired normal state.

The set point is selected by a combination of refractive index of thefilling medium and level of the posterior filling thickness 508. Theselection of optical power under these conditions is straightforwardcalculations in the art. However, appreciation of the accommodativestate of the patient's eye prior to implantation is a consideration inselecting accommodative gain and accommodative range. In general, thereare a variety of combinations of filling medium refractive index andposterior filling thickness which will produce a single desired opticalpower set point. In any case, the optical power set point is determinedby the following procedure:

-   -   1. Decide on a particular set point power based on the patient's        pre-implantation accommodative state.    -   2. Using

$\varphi = {\frac{1}{f} = {( {n - 1.33} )\lbrack {\frac{2}{R_{1}} - \frac{( {n - 1.33} )d}{{nR}_{1}^{2}}} \rbrack}}$

-   -   And substituting the desired set point power for φ, calculate R1        for d=0. All of the IOL embodiments of the present invention        have d approximately equal to zero.    -   3. Determine the volume of filling medium required to obtain R1.        In general, this is a function of a number of IOL parameters,        but these calculations are routine in the art.    -   4. Then the desired set point is approximately obtained when        posterior side 508 comprises one half of the calculated filling        volume.

IOL Pre-Operative Method Example 7

This example concerns selection of accommodative gain of the IOL of thepresent invention. The accommodative gain is the degree of change in φwhen R1 is changed. In a patient, the accommodative gain is readilymeasured by measuring the optical power of the eye, or alternatively thefocal length, and the anterior radius of curvature of the crystallinelens when the ciliary muscles of the eye are dilated and when theciliary muscles of the eye are contracted. A more precise approach is tomeasure both the anterior and posterior curvatures of the crystallinelens. Performing these measurements yield a result

$\frac{\Delta \; \varphi}{\Delta \; R_{1}} = \gamma$

where Δφ is the range of optical power measured (accommodative range),ΔR₁ is the range in anterior crystalline lens curvature, and γ is theaccommodative gain.

It should be clear to those in the art that a normal range of values foraccommodative gain can be empirically derived with which to compare apathologic instance of accommodative gain. Let γ_(o) be the normalaccommodative gain, γ_(p) be the accommodative state of a patient, andγ_(IOL) be the accommodative gain of the implanted IOL, then to return apatient to a normal accommodative state γ_(IOL) must be selected suchthat

is satisfied. Now the gain of the IOL is given by

$\gamma_{IOL} = {\frac{\Delta \; \varphi}{\Delta \; R_{1}} = {{( {1.33 - n} )\lbrack \frac{2}{R_{1}^{2}} \rbrack} = \frac{\gamma_{o}}{\gamma_{p}}}}$

where n is the refractive index of the filling medium and R1 is theanterior radius of curvature of the capsular interface for a givenfilling volume. Thus n can be adjusted to satisfy a desired fillingvolume or conversely to determine a desired accommodative state γ_(IOL).

IOL Volume Set Method Example 8

In general practice injection volume can be selected prior to surgerybased on average experience or more precisely upon the patient'spre-treatment accommodative state. In what follows is described aperi-operative procedure for adjusting injection volume to a particulardesired state of the IOL.

This example concerns selection of injection volume of the IOL and thesuspension of the present invention. As describe previously, a novelaspect of the present invention over prior art IOL's is the preferredoption to suspend the capsular interface within the capsule of a naturaleye. Suspension, as opposed to compression, fitting of the IOL in thecapsule of a natural eye enhances in the former case and degrades in thelater case the accommodative range of the eye. In the preferredembodiments, the equatorial circumference of the capsular interface islined on its exterior surface with a thin band of porous materialdesigned to promote localization. Peri-operatively, proteinaceous fluidsare present in the lens capsule after removal of the fibrous lens whichinteract with this localization band to fix the capsular interface tothe cranial and caudal extremes of the capsule of the natural eye. Whilethe patient is in a recumbent position, the juxtaposition of thelocalization band of the present invention with the desired extremelocations of the natural capsule is automatically achieved when thefilling medium is introduced into the capsular interface. The pressureof the filling medium will ensure proper apposition of the tissue to thedevice and rapid fixation. In general, fixation will occur before theprocess of filling the capsular interface with medium is complete. Thisfixation is a desired step before proceeding with final selection of thevolume of the filling medium.

In general, the clinician optimizes between optical power set point,accommodative gain and accommodative range. The accommodate gain γ andrange Ω are correlated in the following way:

$\gamma_{IOL} = {\frac{\Omega_{IOL}}{\Delta \; R_{1}} = {\frac{\Omega_{o}}{\Delta \; R_{o}}\frac{\Delta_{P}}{\Omega_{p}}}}$

where Ω_(o), ΔR_(o), ΔR_(p), Ω_(p) determine optical power set point.Once determining optical power set point, then accommodative gainγ_(IOL) and range Ω_(IOL) can be optimized such that ΔR₁ satisfies

$\gamma_{IOL} = {\frac{\Omega_{IOL}}{\Delta \; R_{1}}.}$

Once ΔR₁ is determined, standard optical equations can be used todetermine the injection volume.

IOL Accommodation Set Method Example 9

In general practice optical power set point, accommodative gain, andaccommodative range can be selected prior to surgery based on averageexperience or more precisely upon the patient's pre-treatmentaccommodative state. There are a variety of ways to achieve these endpoints, but with respect to a simplified implantation kit designed totreat most patients the injection volume is preferably fixed as is thematerial of the capsular interface. Consequently, the principle meansfor adjusting accommodative power will be selection of the appropriateindex of refraction from a set of standardized separately packagesfilling media. Since in this simplified implantation kit only oneparameter (index of refraction of the filling medium) will be tailoredto the patient, the clinician must select a target value among opticalpower, accommodative gain, and accommodative range. In practice, it isanticipated that generally the clinician will select an accommodativegain sufficient to allow the natural accommodative response of the eyeto achieve near perfect optical power and accommodative range. This willallow for perfect acuity for both near and far accommodation. In whatfollows is described a peri-operative procedure for adjusting injectionvolume to a particular desired state of the IOL.

This example discloses methods of implantation in peri-operativeadjustment of optical power set point, accommodative gain, accommodativerange and injection volume. There are many aspects to the relationbetween a natural lens and the surrounding optical structures of anatural eye, and these are known generally in the art. For example, itis desirable to select an injection volume that does not result in thenatural capsule of the eye in contact with the iris. More generally, itis desirable to the fill the IOL of the present invention such that thenatural flow of aqueous human anterior to the IOL is not altered and theintraocular pressure of the eye is within a normal range.

Accordingly, implantation of the present invention comprises thefollowing steps:

-   -   1. (Optional) It is standard practice to fill the capsule of the        eye with a viscoelastic fluid (Healon®, sodium hyaluronate,        Abbott Medical, USA) prior to placement of an IOL to deepen the        anterior chamber and to open the capsular bag. This practice        does not interfere with the steps listed here, but one should        expect a substantial portion of the fluid to flow out of the        capsule as the capsular interface is filled.    -   2. Prepare an introducer comprising the following features: a        blunt distal end, a hollow shaft, a proximal end fitted with        luer-type connection, to which is attached a syringe filled with        saline.    -   3. Mount the capsular interface on the introducer element that        provides for minimal cross section during introduction of the        rolled capsular interface into the natural capsule of an eye.        The mount should provide fluid connection between the capsular        interface and the syringe.    -   4. Deploy the capsular interface within the natural capsule of        the eye by slightly inflating the capsular interface with        saline. Provide enough saline to cause the equatorial perimeter        of the capsular interface to be in juxtaposition with the        equatorial circumference of the natural capsule of the eye. This        begins the suspension process whereby the capsular interface        bonds to the posterior surface of the natural capsule adjacent        but posterior to the equatorial plane of the natural capsule of        the eye.    -   5. Once the capsular interface is stably located within the        natural capsule the fluid may optionally be withdrawn and        replaced by a fluid with the selected index of refraction, or        optionally this fluid may be used initially.    -   6. The surgeon then places a beam of light through the IOL and        images the beam on the fundus. The surgeon can then monitor the        focal extent of the beam as the IOL is inflated.    -   7. During IOL inflation, the surgeon can check with regard to        various physiological aspects and as well optical aspects        achieved as a result of filling the IOL to a level corresponding        to the posterior filling volume.    -   8. Subsequently, the surgeon can fill the IOL to its full target        volume and check anatomical and optical features.    -   9. Subsequent to these checks, the surgeon withdraws the medium        and prepares the final filling medium.    -   10. Steps 5-7 are repeated, providing for polymerization of the        filling medium between steps 6 and 7.

IOL Capsule Repair Method Example 10

Occasionally, during capsulorrhexis creation, lens removal, IOL deliveryand other surgical manipulations the natural capsule of the eye tears.This risk is enhanced for capsular interfaces which are rigid or includeinternal structure. One advantage of the present invention is that thenatural capsule of the eye is filled to a normal physiologic volume.This has several beneficial outcomes, the principal benefit being therestoration of a natural volumetric and baric relation between theaqueous and vitreous humor of the eye. However, in the case of aperi-operative capsular tear the natural form introduced by inflatingthe IOL of the present invention provides a convenient surface on whichto repair such a tear. In many cases the natural bonding that occursbetween implant and living tissue allows for natural healing of the tearbecause the torn ends can be place in juxtaposition on the implant form.Since the implant retains this form, the pressure applied to the tornregion could be quite small, provided the tear is somewhat distant fromthe equatorial circumference of the capsule. Alternatively, variousabsorbable or non-absorbable tissue adhesives could be used sparingly tohold the tissue in place during healing.

IOL Revision Method Example 11

There is a plethora of reasons why an implant may need to be removed. Inmost cases the IOL of the present invention can be removed in the sameway the natural lens is removed within the capsule of a natural eye. Inmost cases, the filling medium of the capsular interface can be removedby gentle suction without the need for emulsification. In some cases,the capsular interface will need to be removed. In this case thecapsular interface is deflated and drawn into a catheter or rolled to areduced cross section around a pick device.

With respect to the localization pads of the present invention, thesecan be designed with an open cell porosity which will provide anchoringwithout attachment to the pad substrate. The substrate is preferablyhydrophilic but resistant to protein deposition and attachment.Polyurethane foam is a suitable material. Restriction of thelocalization mechanism to the porosity of the pad, and by controllingthe amount of substrate material between adjacent pores providescontrollable tear strength. Thus if removal is required, a thin layer ofthe substrate of the pads is torn away releasing the IOL. Thecombination of being located far from the center of view, small discretesize, and hydrophilicity of the pad substrate ensures any tissuereaction is minimal and local.

In the case of posterior capsule opacification, the standard method oftreatment is Nd:YAG laser posterior capsulotomy wherein the focus of thelaser beam is placed slightly behind the posterior surface of thecapsule and tissue is ablated. There may be additional ablations wherethe focus is successively moved anteriorly until the desired puncture isachieved. Although the posterior wall of the capsular interface isadjacent the posterior surface of the natural capsule, the treatmentlaser wavelength, which is typically around one micron, will not damagethe capsular interface and will be preferentially absorbed by thenatural capsule. Light anterior to the focal point will be absorbed bythe filling medium, but neither the energy density nor the wavelength issufficient to disrupt the polymeric structure of the filling medium. Theabsorption of laser light by the filling medium is insufficient torender ineffective the ablative efficacy of the laser at the focalpoint. Therefore, the standard method of laser ablation to removeposterior opacity of the capsule is not contra-indicated in patientsreceiving the devices of the present invention. However, the etiology ofthis condition is believed to be reduced or eliminated in the presentinvention since implants described herein provide for lubricious contactbetween the capsular interface and posterior surface of the capsule, theimplant is designed to follow capsular movement rather than abradeagainst it, and the material of the capsular interface is morehydrophilic than most IOLs and less likely to induce fibrosis.Furthermore, if a laser should be focused in the interior of the fillingmedium, while the medium is structure it contains an aqueous phase. Anychange in clarity of the filling medium at the point of the laser focusis likely to dissipate out of the field of view.

The following is a list of the general features of the present inventionwhich may be modified to achieve configurations selectable forparticular patient needs.

Capsule Interface

One of the primary objects of the present disclosure is to provide anIOL which does not work against accommodation and avoids applying aradial force directed outwards near the equatorial plane of the capsule.

The material of the capsule interface may be polyurethane, silicone,polyether ether ketone (PEEK) or any colorless organic polymerthermoplastic and mixtures thereof. The capsular interface may be formedby injection mold, solution cast, reaction in mold, thermal injection,and other methods for forming plastic. In particular, solution castingon a mandrel utilizing a prepolymer such that the layer formed on themandrel is high cross linked provides exceptional durability. If apolyurethane is used an aliphatic polyurethane is preferred over anaromatic polyurethane due to the latter's propensity to yellow. Aromaticpolyurethanes tend to be more durable and anti-oxidants can be used tominimize the occurrence of yellowing. In general, a slightly tintedplastic will not be noticed by the patient provided there are noinclusions or bubbles in the plastic.

One of the objects of the present disclosure is to provide an IOL thatdoes not interfere with accommodation. The eye accommodates by reducingthe equatorial axis of the natural capsule of the eye. As a result, theequatorial circumference of the capsular interface needs to decrease inlength in order to follow accommodation. The capsular interface shouldbe extremely elastic and thin walled, preferably between 1 and 25microns in thickness. Generally one selects a capsular interface with anequatorial diameter less than the equatorial diameter of the naturalcapsule, preferably with a circumference 5-15 percent less than theinner surface of the corresponding natural capsule. When the capsularinterface is implanted it is subsequently filled with liquid. The actionof gravity may cause the liquid to spread and thus exert radiallydirected force which may tend to stretch the capsular interface, puttingthe entire surface in tension. This achieves two aims: 1) when inaddition the capsular interface bonds to the equatorial circumference ofthe natural capsule the capsular interface becomes suspended within thenatural capsule and when the patient is standing the forces applied onthe suspensory ligament through the natural capsule are directedradially toward the center of the lens, and 2) accommodation by theciliary muscles causing them to contract and thus relaxing tension inthe zonules results in the tension in the capsular interface to reduceand accordingly the equatorial diameter reduces.

In addition, or alternatively, the capsular interface can be made toreduce its diameter or circumference without inducing folding at theperiphery by providing for a corrugated peripheral structure. Referringto FIG. 6, capsular interface 600 is shown in sectional view takenperpendicular to the axis of the lens. The periphery 602 is the joinbetween anterior and posterior halves of the capsular interface 600.Molded into the form are scallops 604 with localization pads 606 locatedat the maxima of the scalloped pattern 604. Alternatively, especiallywhere localization of the equator of the present invention relative tothe equator of the capsule is difficult or impractical, the pads areplaced posterior to the capsular interface equator. This is a preferredposition since it will be less likely it will interfere withaccommodation. The capsular interface 600 bonds to the inner surface ofthe natural capsule 608 selectively at the localization pads 606.Accordingly, as the natural capsule 608 naturally contracts 610 thedistance 612 between adjacent localization pads 606 reduces. Thisstructure provides a low stress means to provide for naturalaccommodation, and further reduces any resistance to naturalaccommodation. Preferably, corrugations are formed outside the opticalpupil so as not to distort the image perceived by the eye. In thismanner the corrugations outside the viewing pupil facilitate deformationof the portion of the capsular bag outside the viewing pupil toaccommodate the change in shape of the lens during accommodation. It isalso contemplated that similar effects could be achieved by formingdifferent portions of the bag from materials having differentproperties. For example, the area of the bag within the viewing pupilarea may be made of a material that is less elastic than the portions ofthe bag outside the field of view. In this manner the portions of thebag outside the field of view which are more elastic may stretch duringaccommodation to change the shape of the bag, while the bag surfacewithin the viewing pupil is not distorted and so does not alter theoptical properties of the bag within the viewing pupil.

As described herein, the capsular interface has a degree of elasticityso that as the ciliary muscles flex, the capsular interface filled withfilling material alters shape to act as an accommodative lens. The opticdefined by the capsular interface filled with filling material startswith a defined optical power, which is altered as the device changesshape in response to the action of the muscles. That is, with thecapsular interface inserted into the capsular space and filled, theshape and material (e.g., index of refraction) of the capsularinterface, together with the index of refraction of the filling mediumdefines a lens of precise optical power. In one embodiment, a range ofcapsular interface devices are provided so that the surgeon, eitherbefore or at the time of surgery, selects the appropriate capsularinterface material and shape which, when filled with the fillingmaterial, will provide a optic of the desired optical power for theparticular patient's anatomy. Thus, the final, biconvex shape of thecapsular interface could vary, depending upon the exact optical powerdesired of each lens. In this way, the lenses could come in a variety ofshapes, and thereby in a variety of refractive powers. In addition, thecapsular interface materials selected could each have a slightlydifferent index of refraction. This variety could allow for the creationof lenses with similar shapes, but with different optical powers,depending upon patient requirements. Finally, the capsular interfacecould extend inside the lens, to create complex layering (honey-combing)inside the body of the lens, which could allow for various dioptricpowers of the lenses. In a further embodiment, the capsular interface ismade of multiple layers of material, which may be made of the samematerial or two or more different material, which define physicalcharacteristic or shapes which at least in part define the optical powerof the device. Thus, the various layers may be made of materials ofdifferent indices of refraction to help define the power of the device.Alternatively, or in addition, the multiple layers could include shapes,grooves, etc. to add optical power to the optic.

Centering Mechanism

The centering mechanism is largely based on the volume of the IOLrelative to the volume of the capsule, which in the preferred case isnearly equal. In this case, pressure from the aqueous and vitreoushumors as well as the suspensory ligament are naturally equilibrated. Inthe prior art, the replacement lens is substantially less volume thanthe natural lens, this depressurizes the aqueous and vitreous humor andreduces their ability to provide the usual centering mechanism.

Filling Medium

The filling medium provides centering, volume, index of refraction,defines anterior and posterior radii of curvature, and provides anatural dynamic response to accommodative changes in the suspensoryligament. It is therefore important that the filling medium resistgravitationally induced asymmetry, yet provide for symmetricalcompliance.

The filling medium is preferably bi-phasic, comprised mostly of waterand a small structure component of polymeric chains. The water comprisesbetween 50 and 95% of the total volume, with the remainder occupied bypolymeric solids. There are a variety of structured organic andinorganic prepolymers suitable for the present invention. It ispreferred that the filling medium be delivered to the implanted capsularinterface as a prepolymer which then polymerizes in situ.Poly-urea-urethanes are ideal for this purpose, and a variety ofprepolymers are commercially available. The advantage of the polymericsystems is that they do not degrade readily in the body. There are avariety of UV curing polymer available that are also suitable.

Preferably, the structural geometry of the filling medium possess thefollowing features: 1) the prepolymer is able to bond to anterior andposterior inner surfaces of the capsular interface and 2) that somedegree of cross linking occurs such that linear chains disposed betweenanterior and posterior inner surfaces of the capsular interface arelinked laterally. This later point may be significant in the context ofan IOL formed in situ. Thus, a patient is typically positionedhorizontally on their back for surgery, the natural lens is removed andan IOL is implanted. In the case of a traditional, preformed implant,the implant is inserted, the incision is made water tight, and thepatient is permitted to ambulate. With an in-situ formed implant,however, if the implant is not sufficiently cured or is not polymeric,when the patient ambulates the change in gravitational force fromanterior-posterior while the patient is horizontal to cephalad-caudadwhile the patient ambulates, may adversely affect the shape of theimplant and, further, the accommodative function of the lens. Not allthe polymeric chains must be bonded to both anterior and posteriorsurfaces, and not all of the polymeric chains need to be cross linkedlaterally. Thus a mixture of di-functional and tri-functional or greaterprepolymers are useful. The effect of these polymeric links is toprevent asymmetric sagging of the capsular interface. In particular, forthe polymer to dilate in the anterior-posterior plane the polymer mustcontract in the equatorial (cranial-caudal) plane.

Enhanced anterior-posterior dilation and consequently increased gain canbe achieved without introducing asymmetry due to gravity by providingfor anterior-posterior links primarily through anterior bond chains andseparately posterior bonded chains linked through lateral bonds.Furthermore, a minority of free chains may be interposed to provide forgreater mobility requiring less accommodative force to achieve a desiredchange in radial curvature of the anterior and posterior sections of thecapsular interface. More complex geometries can be achieved by varyingthe ratio of anteriorly bonded chains to posteriorly bonded chains sothat the radius of curvature on the anterior side is greater or lessthan the radius of curvature on the posterior side. In this way an IOLimplant can be constructed that maintains a variety of ellipsoidalgeometries as well as compound geometries which are more ellipsoidal onthe periphery and more spherical at the center. Accordingly, thepreferred prepolymer mixtures of the present invention when filled intoa capsular interface possess an internal structure that tends tostabilize the shape of the IOL in an ellipse with an aspect ratio<0.6,and more preferably between 0.45 and 0.6.

Biocompatibility

In addition to selecting relatively inert and stable compounds forimplantation, it is desirable the surface of the IOL follows withoutrelative motion changes in shape of the natural capsule. Abrasionbetween an implant and the natural capsule can cause fibrosis andopacity, which when in the field of view obscures vision.

Additionally, the exterior surface of the IOL, especially the posteriorsurface, may be coated with a lubricous material designed to mitigateirritation of the capsule and reduce posterior capsular opacificationtypically associated with IOLs. Suitable lubricious materials aresilicone oils, placed peri-operative behind the implant or bondeddirectly to the implant. There are a variety of techniques known in theart for bonding lubricous surfaces, such as silicone oil, to anelastomeric substrate. Preferably, the area of lubricity is located awayfrom the area of localization of the present invention.

Ultra-Violet Protection

It is standard practice to add chromophores to IOLs to reduce theintensity of ultra-violet light transmission through an IOL. All theembodiments of the present invention can have chromophores added to thefilling medium prior to solidification within the capsular interface.Compatible chromophores include benzotri-azole benophenones with anabsorption spectrum extending to wavelengths as long as 400 nm.

The methods and systems of the present invention, as described above andshown in the drawings, provide for IOL devices and methods with superiorproperties including improved functional approximation of a healthylens. While the apparatus and methods of the subject invention have beenshown and described with reference to preferred embodiments, thoseskilled in the art will readily appreciate that changes and/ormodifications may be made thereto without departing from the spirit andscope of the subject invention.

What is claimed is:
 1. A physiologically adaptive intra-capsular opticcomprising: an injectable filling medium; and a capsular interfaceconfigured and dimensioned to be received within the natural eyecapsule, and to be filled with the injectable filling medium, whereinthe capsular interface filled with the filling medium defines a firstoptical power, wherein the capsular interface filled with the fillingmedium is an elastic accommodative lens so as to respond to action ofthe ciliary muscles and adjust to an altered shape.
 2. An intra-capsularoptic as recited in claim 1, wherein the capsular interface and thefilling medium define a second optical power of the elasticaccommodative lens in the altered shape after responding to action ofthe ciliary muscles.
 3. An intra-capsular optic as recited in claim 1,wherein the first and second optical powers are predetermined by atleast the shape and refractive index of the capsular interface, and therefractive index of the injectable filling medium, such that the firstand second optical powers vary depending on the shape and refractiveindex of the capsular interface, and the refractive index of theinjectable filling medium.
 4. An intra-capsular optic as recited inclaim 1, wherein the capsular interface is at least one of rolled orfolded and inserted through a small incision in the eye and filled insitu by injecting the filling medium into said capsular interface.
 5. Anintra-capsular optic as recited in claim 4, wherein the injectablefilling medium changes from a liquid state to a solid state.
 6. Anintra-capsular optic as recited in claim 5, wherein the said solid stateis structured and biphasic comprised of between 50 and 95% liquid and asolid distributed state.
 7. An intra-capsular optic as recited in claim6, wherein anterior and posterior inner walls of said capsular interfaceare bonded at least partially to the bi-phasic filling medium.
 8. Anintra-capsular optic as recited in claim 7, wherein the filling mediumis a silico-urethane prepolymer comprised of a block polymer containingat least one silicon containing block and at least one ethylene oxidecontaining block.
 9. An intra-capsular optic as recited in claim 1,wherein the capsular interface further comprises a deployment means suchthat when the capsular interface is filled with the filling medium, theconduit for delivery is sealed, and the delivery means is detached fromsaid capsular interface.
 10. An intra-capsular optic as recited in claim9, wherein the deployment means includes a catheter, and the interiorvolume of the capsular interface is fluidically connected to saidcatheter.
 11. An intra-capsular optic as recited in claim 9, wherein thecapsular interface includes a valve for sealing the conduit fordelivery.
 12. An intra-capsular optic as recited in claim 1, wherein thefilling medium has a microscopic structure resembling stacked rods withpivotal interconnect.
 13. An intra-capsular optic as recited in claim12, wherein the density of said pivotal interconnections is varied toobtain a desired optical power.
 14. An intra-capsular optic as recitedin claim 6, wherein said liquid fraction is selected to obtain a desiredoptical power.
 15. An intra-capsular optic as recited in claim 1,wherein at least one of the filling medium or the material of thecapsular interface is selected to obtain a desired optical power.
 16. Anintra-capsular optic as recited in claim 12, wherein the material of thecapsular interface, the density of pivotal interconnections, and therefractive index of the filling medium provides an optical power rangeof approximately 15 diopters.
 17. An intra-capsular optic as recited inclaim 16, where in the index of refraction of the filling medium isselected by the clinician to provide a lens with a wide range of meandioptric powers.
 18. An intra-capsular optic as recited in claim 1,wherein the capsular interface is filled to obtain an aspect ratio lessthan 0.6.
 19. An intra-capsular optic as recited in claim 18, whereinthe capsular interface when filled has dimension of approximately 4 mmanteroposteriorly and 9 mm equatorially.
 20. An intra-capsular optic asrecited in claim 1, wherein the capsular interface is scalloped on theequatorial periphery.
 21. An intra-capsular optic as recited in claim 1,wherein the capsular interface is coated with a medication.
 22. Anintra-capsular optic as recited in claim 1, wherein at least part of thefilling medium contains a medication and the capsular interface isselectively permeable to the medication.
 23. An intra-capsular optic asrecited in claim 1, wherein the shape of the optic is defined at leastin part by the capsular interface, and the shape defined by the capsularinterface at least in part defines the optical power of the optic. 24.An intra-capsular optic as recited in claim 1, wherein the capsularinterface includes multiple layers which in combination at least in partdefine the optical power of the optic.
 25. An injectable,physiologically adaptive intra-capsular optic comprising an injectablefilling fluid and a capsular interface, said capsular interfacecomprising an internal optic disposed such that said internal optictranslates along a central line of vision in response to physiologicchanges of an eye.
 26. An intra-capsular optic as recited in claim 25,wherein said internal optic is bistable and translates from a firstanterior position to a second posterior position in response to externalpressure applied to the eye and conversely, said second posteriorposition translates to said first anterior position in response toexternal pressure applied to the eye.
 27. An intra-capsular optic asrecited in claim 1, wherein a portion of the capsular interface withinthe field of view is less elastic than a portion of the capsularinterface outside of the field of view.
 28. An intra-capsular optic asrecited in claim 1, wherein the capsular interface extends in ahoneycomb pattern within the optic into the filling medium, and whereinthe first and second optical powers are predetermined by at least thehoneycomb pattern, such that the honeycomb pattern is used as a variableto generate various dioptric powers of the lens.
 29. An intra-capsularoptic as recited in claim 1, wherein the injectable filling medium is anin-situ polymerizing filling medium.
 30. An intra-capsular optic asrecited in claim 1, wherein the shape of the optic is defined by thecapsular interface, and the shape defined by the capsular interface atleast in part defines the optical power of the optic such that the optichas a predetermined optical power.